AsianScientist (Jun. 30, 2020) – In a critical step toward creating a global quantum communications network, researchers have generated and detected quantum entanglement onboard a CubeSat nanosatellite smaller than a shoebox. These results, by a team led by scientists at the National University of Singapore (NUS), have been published in Optica.
Entanglement is a unique quantum mechanical phenomenon in which two particles are inextricably linked. The particles exist such that measuring one in isolation immediately allows you to know the state of the other, regardless of how far the two may be separated. This strange phenomenon, which forms the basis of modern quantum computing, was once described by Einstein as ‘spooky action at a distance,’ as it implied that action upon one object could intimately affect something else far away.
Scientists hope to exploit this property to build a quick, more secure Internet. Currently, fast Internet is carried via fiber optic cables that transmit data. This data takes the form of photons, which can be thought of as particles of light. However, physical limitations on size, distance and complexity mean that signals may be lost. At most, cables may only traverse a few tens of kilometers.
Using satellites instead may increase the potential for connectivity by several orders of magnitude. Therefore, Dr. Aitor Villar, a recent graduate from NUS’ Centre for Quantum Technologies (CQT), designed SpooQy-1, a nanosatellite that can orbit 400km above Earth.
SpooQy-1 and other similar nanosatellites generate pairs of photons such that they are entangled. The plan is to send one particle from each pair of photons to two ground stations on Earth. Due to their linked nature, receivers on Earth can immediately infer the state of the other photon, allowing for an instantaneous transfer of information.
The researchers demonstrated that SpooQy-1 can operate successfully in space, generating quantum signals that could withstand the harsh conditions of launch and orbit.
“In the future, our system could be part of a global quantum network transmitting quantum signals to receivers on Earth or on other spacecraft,” Villar said. “These signals could be used to implement any type of quantum communications application, from quantum key distribution for extremely secure data transmission to quantum teleportation, where information is transferred by replicating the state of a quantum system from a distance.”
This research in the footsteps of the high-profile experiments by China’s Micius satellite, which managed to send intertwined quantum particles to stations separated by 1,120km. Notably, however, Micius weighed approximately 640kg, significantly heavier than SpooQy-1, which is smaller than a shoebox and weighs only 2.6kg. Nanosatellites like SpooQy-1 consume very little power and may pave the way for cost-effective telecommunications.
“At each stage of development, we were actively conscious of the budgets for mass, size and power,” said Villar, explaining why the team chose to use off-the-shelf components.
The next phase of the project includes a joint project between Singapore and the UK. CQT will be collaborating with RAL Space in the UK to design and launch a satellite similar to SpooQy-1 that can beam entangle photons from space to a ground receiver by 2022.
Source: Centre for Quantum Technologies.
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